System for scrubbing coal gas



A. F. MESTON SYSTEM FOR SCRUBBING GOAL GAS Filed Dec. 17, 1918 2 shets-sheet l Feb. 6, 1923.

A. F. MESTON SYSTEM FOR SCRUBBING COAL GAS Filed Dec. 17, 1918 2 sheets-sheet 2 II 1 iIttIIIl I I II l MOM 0134) Patented eb. 6, 1923.

aaomnatn r. MEsroN. or new SYSTEM FOR SCRUBBING COAL GAS.

Application filed December 17, 1918. Serial No. 267,130.

To all whomz't map concern: 7

Be it known that I, ARCHIBALD F. MESTON, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in a for Scrubbing Coal Gas, lowing is a specification.

The present invention relates to apparatus for detarring gases and more particularly to apparatus for recovering benzol and ammonia.

It is an object of this invention to provide a system of detarring gases by which the various tarry and assoclated constituents can be recovered economically, efi'ec-tively and in a state of comparative urit It is the more particular ob'ect to provide apparatus for effectively an economically removing ammoniaand benzol.

For a fuller understanding of the principles upon which the invention is based, of the mode of operation and the result, reference is had to the accompanying drawings, in which 1 Fig. 1 is a. diagrammatic representation of a detarring system embodying the invention;

Fig. 2 a sectional view of an absorbing tower formin an essential part of the system shown infFig. 1;

Fig. 3 a fragmentary sectional view of an electric treater unit employed; and

Fig. 4 a fragmentary view of a detail.

The hot tarry gases which come from a retort or coke oven pass through a pipe 1 to a cooling device, preferably a heat exchanger 2 where they are cooled to a temperature at which'the water carried is still in vapor form, say slightly above 100 C. The gases thus cooled are then passed into an electric p-recipitator 3 of the usual or any preferred design where the greater part of of which the folthe tar is removed while the water remains in the gas. The gases are next passed into a washer 6, a fan 5 being preferably placed into the connecting pipe 4 to force the gas through the system. In the washer 6 the gases are subjected to a spraying device 7 by which they are thoroughly washed and cooled, the excess of water being removed by condensation and entrainment. A cooler in which the cooling agent does not come in contact with the and may be substituted for the one shown.

System gas has certain advantages While it is now possible to pass the gases cllrectl to the ammonia scrubber, it is consldere best to pass it first through a second electrical precipitator 8 in order to remove and benzol. A cooler may be placed between ammonia scrubber 10 and the benzol washer.

11 if found advisable.

The ammonia scrubber 10 and the benzol washer 11 are substantially identical in structure and principle of operation. A detail description of one applies therefore equally to the other.

Having now reference to Fig: 2, the device represented includes principally three parts, a chamber containing checker work, a spraying device and an electrio precipitator.

The chamber 12containing the checkerwork 13 may be of the usual design. In the spray chamber 14 is disposed a spraying mechanism 15 for discharging absorbent which may be a suitable wash oil. The manner in which and-the mechanism by which the absorbent is discharged is not material provided the discharge takes place in the form \of a fine mist which is essential for a full realization of the advantages of the invention. There are several reasons for discharging the absorbent in a highly atomized condition or in a fine mist. One is based on YORK, N. Y., ASSIGNOR T0 RESEARCH CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

pass into the I the fact that in this condition it presents an state of suspension. When exposed to a gas stream they are easily entrained and carried ber descends into the passages of the checkerwork, being compelled to do so by the pressure of the successively discharged particles. The gas-entering through the nlet 16 and coming up through the passages of the checkerwork passes through the fine mist filling these passages and deposited on the checkerwork with the result that most of the benzol is absorbed in this part of the ap aratus.- As the gas in a successively puri ed condition passes up and finally enters the spraying chamber, it is forced to penetrate the fine mist of absorbent llqllld ust formed and still free of benzol. In passing through the upper zone of the mist the gas stream entrains a considerable quantity of the fine mist particles and carries them upwardly into the electric field of the prec pitator 17 immediately above the spraying chamber.

During the upward motion of the fine mist particles, which are at the instant of entrainment entirely free of benzol, the last traces'of benzol are absorbed. This process of absorption is greatly facilitated by the action of the electric field which causes, as is well known, a migration of the suspended particles transversely of the gas stream and thereby brings about a thorough mixing with the gases. To this final 'nixing of the pure absorbent mist with the gases is to a great extent due the complete absorption of the benzol in the gas. In the precipitator 17 the mist is, together with the absorbed benzol, precipitated against the receiving electrodes 17 and the liquid formed flows down the walls .thereof into the chamber containing the checkerwork, where it .increases appreciably the quantity of absorbent directly received from the spraying chamber. Since this liquid coming from the electrical precipitator 17 is only comparatively slightly charged with benzol, having absorbed only the last traces thereof, it has considerable absorptive capacity and takes the place of a similar quantity of absorbent liquid which would have to be supplied by the spray chamber directly. The saving in absorbent liquid is thereby considerable.

This dual function of the mist entrained by the gasfto first operate to remove those benzol remnants which escape absorption in the checkerwork and in the spray chamber, and then to take part in the function of the checkerwork chamber, is that feature which most characterizes the invention. a While, as before stated, the specific form of mist-forming device is not material to the invention, I found that the arrangement shown in Fig. 4; gives satisfaction when used to dispense viscous liquids which are difficult to spray with ordinary nozzles. The absorbent is passed into the spray chamber issuing gas stream intercepts the liquid chamber and to be distributed therein.

by means of a pipe or pipes 20, controlled b a valve 21 and discharged through noz' zles 22.. Cleaned gas may be discharged through a nozzle 23 so positioned that the discharged from the nozzles 22. The pressure necessary for the atomization may be reduced in the usual manner as for instance y a pressure pump 24.

The electrical precipitator may consist of a plurality of receiving electrode tubes 17' arranged-in rows in the usual way. The discharge electrodes .18 are suspended from bus bars 19 which in turn are supported on insulators 25. In order to protect the insulators 25 as much as possible against the effects of a conductive deposit, they are placed under hoods 25 and are mounted in housings 26 substantially isolated from the gas stream.

The tubes 17' have preferably a flaring lower end to which is attached a conical screen 17 This arrangement has the advantage that it facilitates the mixing of the fine mist particles entrained by the gas stream with the gas and thereby promotes the absorption of the last traces of the gas which have not been absorbed in the absorption chamber or in the spray chamber. The-discharge electrodes 18 are preferably rigid so as to maintain their normal posi tion in the tubes 17.

Absorbent liquid may also be supplied, if found desirable, by an auxiliary discharge system 28. There is. of course, considerable latitude as to detail.

As-has been previously stated, the ammonia scrubber 10 is similar in every respect to the benzol washer just described. Instead of a wash oil, however, dilute sulphuric acid is atomized to form a mist, as is well known.

The liquid charged with the absorbed benzol and toluol or ammonia respectively is drawn off in the usual way by aliquidseal drain 27 It is understood that the invention is not limited to the recovery of ammonia or benzol and toluol from coal gases. It is applicable in all cases where a gas is to be separated from another gas by the use of an absorbent liquid.

While I consider the apparatus shown and described as the preferred embodiment, I am fully aware that. in order to derive the advantages of the invention, the precipitator need not be disposed directly above the spray chamber. The term above in the claims is therefore intended to have a broader meaning. It is intended to include all such positions immediately adjacent the spray chamber in which the entrained mist is still carried in suspension by the gas stream and in which it is made possible for the pre cipitated mist to flow 1nto the absorption embodiment of the invention includes mechanism for forming a fine mist in order to derlve the greatest possible advantage, I. consider Within the scope of the invention any device for discharging the absorbent liquid by Which some mist may be earried along by the gas stream.

In the claims, the term absorption chamber is used to define any construction by which a gas stream is brought into inti mate contact With an absorbent medium.

I claim:

1. Apparatus for removing a gas from another gas, comprising an absorption chamber, a spray chamber above the absorption chamber and means therein for discharging an absorbent liquid into the absorption chamber as a fine mist, an electric precipitator above the spray chamber, and means for passing the gas stream to be treated in succession through the absorption chamber, the spray chamber and the electric precipitator.

2. Apparatus for removing a gas from another gas comprising an absorption chamber, a spray chamber above the absorption chamber for distributing an absorbent liquid over the surfaces of the absorption chamber, means in said spray chamber for discharging the absorbent liquid as a cloud or fine mist, an electric preeipitator having a plurality of treater units so positioned that the liquid precipitated therein flows down into the absorption chamber and is substantially uniformly distributed therein, and means for passing the gas stream to be treated in succession through the absorption chamber, the cloud and the precipitator.

In testimony whereof I afiix my signature.

ARCHIBALD F. MESTON. 

